As thin-film electrode materials for semiconductor devices, such as DRAM and FERAM, ruthenium and ruthenium compounds are used. As a method for producing of such a thin film, a chemical deposition method, such as CVD (chemical vapor deposition method) or ALD (atomic layer deposition method), is applied. As raw material compounds for use in such a chemical deposition method, a large number of organoruthenium compounds are conventionally known.
Generally, as a required property of an organoruthenium compound for chemical deposition, to efficiently form a thin film, a high vapor pressure is required. Additionally, considering handleability, it is preferable that the compound is in a liquid state at ambient temperature. From such a point of view, cyclic or linear dienyl-coordinated organoruthenium compounds are used. Many of cyclic or linear dienyl-coordinated compounds have relatively high stability in air and are easy to handle.
Examples of compounds having a cyclopentadienyl group include bis(ethylcyclopentadienyl)ruthenium Ru(EtCp)2 and (2,4-dimethylpentadienyl)(ethylcyclopentadienyl)ruthenium Ru(EtCp)(Me2PD) represented by the following formulae (Non Patent Document 1). Examples of compounds in which two pentadienyl groups are coordinated include bis(2,4-dimethylpentadienyl)ruthenium Ru(Me2PD)2 and bis(1-ethylpentadienyl)ruthenium Ru(EtPD)2 (Non Patent Document 1, Patent Document 1), and, as a compound in which a cyclohexadienyl group is coordinated, bis(2,6,6-trimethylcyclohexadienyl)ruthenium Ru(Me3CHD)2 can be mentioned (Patent Document 2).

In the above formulae, EtCp is ethylcyclopentadienyl,
Me2PD is 2,4-dimethylpentadienyl,
EtPD is 1-ethylpentadienyl, and
Me3CHD is 2,6,6-trimethylcyclohexadienyl.
The above compounds have relatively high vapor pressures, and many are liquids at ambient temperature. In particular, when attention is paid to the decomposition temperature, the decomposition temperatures of Ru(EtCp)(Me2PD) and Ru(Me2PD)2 are as low as about 270° C. and about 210° C., respectively, and thus these compounds can be easily formed into films even at low temperatures.